The Portugal forward looked sharp one day after completing a loan move from Atletico Madrid but he was shown a straight red card in the 58th minute for a reckless tackle on Fulham defender Kenny Tete when the score was 1-1.
Fulham made the most of the man advantage when Brazilian forward Carlos Vinicius, standing in for the club’s suspended top scorer Aleksandar Mitrovic, put the hosts back in front in the 73rd minute with a clever header.
Former Chelsea winger Willian had put Marco Silva’s side in front in the first half with a deflected shot but Potter’s side levelled early in the second half through a scrappy goal from close range by defender Kalidou Koulibaly.
Kai Havertz had a late chance to equalise with a stinging effort but Fulham goalkeeper Bernd Leno was equal to it and Marco Silva’s side saw out the win to climb above Liverpool and up to sixth in the Premier League standings on 31 points after 19 games.
Chelsea, who fell to their eighth league defeat this season and their third consecutive loss in all competitions, are 10th in the table on 25 points from 18 matches.
Additional reporting from Reuters